世界上怪事何其多,为猫和老鼠制作盔甲,你觉得新奇吗?每当见到古人使用的威武盔甲,人们总禁不住啧啧赞叹。若摆放在眼前的是为猫和老鼠量身打造的盔甲,你又会发出怎样的惊叹?很简单,酷。因为它们并非日常生活中宠物身穿的布料衣物,而是由光亮的铜、银等金属制作的货真价实的盔甲。这些精巧的盔甲售价为2000美元至20000美元之间。这还不包括材料费。作者杰夫·德·波尔(Jeff de Boer)的言语中透着一丝骄傲,尽管这些作品的大小甚至顶不上一辆玩具汽车。为猫穿上盔甲其实猫鼠盔甲是精美的艺术品,你可以打开上了铰链的面罩,露出它们的头部,也可以将整个包裹身体的金属盔甲收拢,看起来就像 相似文献
Members of the microbial guanyl-specific ribonuclease family catalyse the
endonucleolytic cleavage of single-stranded RNA in a two-step reaction
involving transesterification to form a 2',3'-cyclic phosphate and its
subsequent hydrolysis to yield the respective 3'-phosphate. The
extracellular ribonuclease from Bacillus intermedius (binase, RNase Bi)
shares a common mechanism for RNA hydrolysis with mammalian RNases. Two
catalytic residues in the active site of binase, Glu72 and His101, are
thought to be involved in general acid-general base catalysis of RNA
cleavage. Using site-directed mutagenesis, binase mutants were produced
containing amino acid substitutions H101N and H101T and their catalytic
properties towards RNA, poly(I), poly(A), GpC and guanosine 2',3'- cyclic
phosphate (cGMP) substrates were studied. The engineered mutant proteins
are active in the transesterification step which produces the 2',3'-cyclic
phosphate species but they have lost the ability to catalyse hydrolysis of
the cyclic phosphate to give the 3' monophosphate product.
相似文献
Cauxin is an abundant protein in feline urine. We have used proteomics strategies to characterize cauxin from the urine of
domestic cats and a number of big cat species. Proteins were resolved by gel-based electrophoretic purification and subjected
to in-gel digestion with trypsin. The resultant tryptic peptides were mass-measured by matrix-assisted laser desorption ionization
time of flight mass spectrometry. Peptides were also resolved by liquid chromatography and analyzed by electrospray ionization
and tandem mass spectrometry to generate fragment ion data to infer the amino acid sequence. We identified cauxin polymorphisms
and corrected a sequencing artifact in cauxin from the domestic cat. The proteomics data also provided positive evidence for
the presence of a cauxin homolog in the urine of big cats (Pantherinae), including the Sumatran tiger, Asiatic lion, clouded
leopard, Persian leopard, and jaguar. The levels of cauxin in the urine of all big cats were substantially lower than that
in the urine of intact male domestic cats. 相似文献
COVER PHOTOGRAPH: Monoclinic pure ZrO2 flash‐sintered compact (A) and SEM images of fixing a needle onto a fractured surface of the compact (B) and picked up grains with a needle (C) and the grain surface (D) by FIB‐SEM. From Morisaki et al. Intergranular amorphous films formed by DC electric field in pure zirconia. DOI: 10.1111/jace.15485 .
Tetragonal [Ba12(BO3)6]6+ cation pattern of the Ba3(BO3)2 structure with channels along c axis and fragment of a channel. Ba, O, and B atoms are shown in blue, red and black, respectively. For disordered (BO3)3– groups inside the channel, occupancy of atoms is shown by partial filling. The drawing was prepared using VESTA software (Momma, K., and F. Izumi. 2011. “VESTA 3 for Three‐Dimensional Visualization of Crystal, Volumetric and Morphology Data.” Journal of Applied Crystallography 44 (6): 1272–76. doi: 10.1107/S0021889811038970 ).
